Styling lighting is widely used in the industrial field, for example, used in a tail lamp, a brake lamp, combination lamp for an automobile, and a display panel for a display. Such lighting devices usually comprise a light-emitting element and a light guide, wherein light emitted from the light-emitting element transmits through the light guide and exits out of the light guide, thereby forming various light shape patterns. However, to meet requirements for pleasant appearance, or requirements for specific light shapes, the light guide usually takes various three-dimensional shapes, e.g., the light guide has a different curvature. How to position the light-emitting element properly with respect to the light guide to achieve uniform illumination is a technical problem urgently to be solved in the art.